My first needs were related to my building projects and included meters for measuring capacitance and inductance. I have excellent-quality bench meters for other hobby projects including a Keithley 192 and 181 voltmeter with IEEE 488 computer interfaces. These are voltmeters only though, nothing else. My first purchase then was a capacitance/inductance meter. It worked great for capacitance, but the lowest range for inductance, 20mH unfortunately is useless. So, this meter was quickly followed by a stand-alone inductance meter ranging down to 200uH. I use these frequently when making or measuring coils, and measuring capacitors purchased on ebay, better to design a radio around a specific componant.
My next needs follow logically, what about the radios I build?, how do they do? For the non-electrical engineer, testing radios is a bit of a daunting task and this page is by no means intended to be a tutorial. I do give my experiences so that perhaps someone with the same idea may benefit and possibly avoid the mistakes I have certainly made. I describe my equipment and the protocols used in my testing, but I STRONGLY refer the reader to the following two pages for technical guidance and explanations, most of what I do came directly from here:
Dick Kleijer crystal-radio.eu http://www.crystal-radio.eu/enqmeting.htm
Gollumīs Crystal Receiver World http://home.snafu.de/wumpus/gollum/testing.htm article by C.A. Lauter
I heartily express my appreciation to our European friends for making available on the web these excellent technical tutorials for crystal radio testing.
Testing and understanding your set from the Antenna at the front, the tank in the middle and on to the Diode at the back and then the Radio complete, the whole shebang!
ANTENNA TUNING UNIT.. Design notes and Models, Effect of earth resistivity..
COIL Q.. Summary of web research on expected values of Q for various coil designs.
COIL Q Revisited.. An Analytical Approach to the measurement of coil Q.
Crystal Radio Capacitors.. A look at capacitor Q and its relation to ESR (Equivelant Series Resistance).
DIODE TEST.. Describes results of testing on many different diodes, diode classes, crystals, and even vacuum diodes.
DIODE PROTOCOL.. Describes a useful protocol for determination of Diode Is, n, and Rd.
DIODE CALIBRATION.. A simple set of modelled characteristics with variations in Is and n.
RADIO TEST.. Describes protocols and results of radio performance testing on my sets.